lexloom

LexLoom 🧵

LexLoom is a cross-platform syntax highlighting meta-compiler. It abstracts the nightmare of writing complex, engine-specific grammar files (Oniguruma for VS Code, procedural regex for Vim, and XML for Notepad++) into a single, clean JSON file.

Define your language once. Generate native highlighters everywhere.

✨ Key Features

• 🧠 Regex-Free Authoring: Define language constructs by intent (e.g., wordList, symbolList, stringMarker) rather than writing platform-specific regular expressions.
• 🌍 Write Once, Highlight Anywhere: Instantly generate highlighters for VS Code (.tmLanguage.json), Vim (.vim), and Notepad++ (UDL .xml).
• ⚡ VS Code Web Extension Scaffolding: Bootstrap a ready-to-use, publishable VS Code Web extension project directly from your grammar.
• 🔋 Batteries-Included Presets: Built-in, highly optimized regex patterns for common needs like decimals, hex numbers, binary, and embedded language injection.

🚀 Quick Start

1. Installation

Install LexLoom globally via NPM to use the CLI anywhere:

npm install -g lexloom

(Alternatively, you can run it without installing by cloning this repo and using npx lexloom)

2. Write your Grammar (my-language.json)

LexLoom uses a standardized JSON format. Here is a taste of how easy it is to define keywords and operators:

{
  "metadata": {
    "name": "My Language",
    "scopeName": "source.mylang",
    "extensions": [".mylang"]
  },
  "rules": [
    {
      "ruleType": "wordList",
      "universalScope": "keyword.control",
      "words": ["if", "else", "function", "return"]
    },
    {
      "ruleType": "symbolList",
      "universalScope": "keyword.operator",
      "symbols": ["==", "!=", "+", "-", "&&"]
    }
  ]
}

3. Build the Highlighters

Run the CLI against your grammar file:

lexloom my-language.json --scaffold-vsc

Output:

out/
├── vscode/            # TextMate .tmLanguage.json
├── vim/               # Vim .vim syntax script
├── notepadpp/         # Notepad++ .xml UDL
└── vscode-extension/  # A complete, ready-to-publish VS Code Web extension!

🪄 Pro-Tip: Instant IDE Autocompletion

You don't need to guess the rule types or scopes. LexLoom comes with a built-in JSON Schema.

Add this single line to the very top of your JSON file in VS Code to get instant validation, hover documentation, and IntelliSense dropdowns for your grammar:

{
  "$schema": "https://raw.githubusercontent.com/thisisthedarshan/LexLoom/refs/heads/main/schema/lexloom.schema.json",
  "metadata": { ... }
}

📄 License

LexLoom is open-source software licensed under the Apache 2.0 License.

Note: The syntax files and VS Code extensions generated by the LexLoom CLI are the sole property of the user and are not bound by this license.